cppDateClass

#include <iostream>

class Date
{
    uint16_t year;
    uint8_t month;
    uint8_t day;

    uint8_t checkMonth(uint8_t monthP)
    {
        if (monthP < 1) return 1;
        if (monthP > 12) return 12;
        return monthP;
    }
    uint8_t checkDay(uint8_t dayP, uint8_t monthP, uint16_t yearP)
    {
        const uint8_t maxDays{ Date::daysInMonth(monthP, yearP) };
        if (dayP < 1) return 1;
        if (dayP > maxDays) return maxDays;
        return dayP;
    }
public:
    static uint8_t daysInMonth(uint8_t month, uint16_t year)
    {
        return 30 + (((month < 8) and (month % 2 != 0)) or ((month >= 8) and (month % 2 == 0))) + ((month == 2) * (-2) + isLeapYear(year));
    }

    static bool isLeapYear(uint16_t year)
    {
        return year % 400 == 0 or year % 4 == 0 and year % 100 != 0;
    }
    static const uint8_t maxMonth{ 12 };

    Date() : Date(1, 1, 1970) {}
    Date(uint8_t dayP, uint8_t monthP, uint16_t yearP)
        : year{yearP}, month{ checkMonth(monthP)},day{checkDay(dayP,month,yearP)} {}

    Date& setDay(uint8_t dayP) { day = checkDay(dayP, month, year); return *this; }
    Date& setMonth(uint8_t monthP) { month = checkMonth(monthP); day = checkDay(day, month, year); return *this; }
    Date& setYear(uint16_t yearP) { year = yearP; return *this; }

    uint8_t getDay() const { return day; }
    uint8_t getMonth() const { return month; }
    uint16_t getYear() const { return year; }

    Date& print() { std::cout << +day << '.' << +month << '.' << year << '\n'; return *this; }
};


int main()
{
    std::cout << std::boolalpha << (Date::isLeapYear(2020) == true) << '\n';
    std::cout << std::boolalpha << (Date::isLeapYear(2021) == false) << '\n';
    std::cout << std::boolalpha << (Date::isLeapYear(1800) == false) << '\n';
    std::cout << std::boolalpha << (Date::isLeapYear(1600) == true) << '\n';
    std::cout << std::boolalpha << (Date::daysInMonth(12, 2021) == 31) << '\n';
    std::cout << std::boolalpha << (Date::daysInMonth(1, 2021) == 31) << '\n';
    std::cout << std::boolalpha << (Date::daysInMonth(4, 2021) == 30) << '\n';
    std::cout << std::boolalpha << (Date::daysInMonth(2, 2021) == 28) << '\n';
    std::cout << std::boolalpha << (Date::daysInMonth(2, 2020) == 29) << '\n';

    Date date1;
    std::cout << std::boolalpha << (date1.getDay() == 1) << '\n';
    std::cout << std::boolalpha << (date1.getMonth() == 1) << '\n';
    std::cout << std::boolalpha << (date1.getYear() == 1970) << '\n';

    Date date2{ 26,7,1981 };
    std::cout << std::boolalpha << (date2.getDay() == 26) << '\n';
    std::cout << std::boolalpha << (date2.getMonth() == 7) << '\n';
    std::cout << std::boolalpha << (date2.getYear() == 1981) << '\n';

    date2.setDay(32);
    std::cout << std::boolalpha << (date2.getDay() == 31) << '\n';
    date2.setDay(0);
    std::cout << std::boolalpha << (date2.getDay() == 1) << '\n';
    date2.setDay(31);
    date2.setMonth(2);
    std::cout << std::boolalpha << (date2.getDay() == 28) << '\n';
    std::cout << std::boolalpha << (date2.getMonth() == 2) << '\n';

    return 0;
}